Tanu Rapria

Bacteria can exist both outside and inside host cells, and understanding the distinction between extracellular and intracellular bacteria is crucial for studying their behavior and impact on various biological systems. This comprehensive guide will delve into the specifics of extracellular bacteria, providing a detailed overview of the methods used to detect and quantify them, as well as the importance of this knowledge in the field of microbiology.

Extracellular Bacteria: Characteristics and Quantification

Extracellular bacteria are those that reside outside of host cells, existing in the surrounding environment. These bacteria can play a significant role in various ecological processes, from nutrient cycling to pathogen-host interactions. To understand the dynamics of extracellular bacteria, researchers have developed several techniques to detect and quantify their presence.

Extracellular DNA (exDNA) Analysis

One of the most common approaches to studying extracellular bacteria is the analysis of extracellular DNA (exDNA). Bacteria release exDNA during growth, death, and lysis, and this DNA can serve as a proxy for microbial activity and abundance. Techniques such as quantitative PCR (qPCR) and flow cytometry can be used to quantify the amount and composition of exDNA in a given sample.

For example, a study by Nagler et al. (2018a) found that exDNA levels in soil samples were positively correlated with the abundance of specific bacterial taxa, providing insights into the ecological relevance of extracellular bacteria in natural environments. The researchers also demonstrated that exDNA can be used to track changes in microbial community structure over time, making it a valuable tool for monitoring environmental processes.

Metabolic Footprinting

Another method for measuring extracellular bacteria is through metabolic footprinting, which involves analyzing the metabolites that bacteria secrete into their environment. This approach can provide information on the physiological state and activity of extracellular bacteria, as well as their interactions with other microorganisms and their environment.

For instance, a study by Wagner et al. (2008) demonstrated the removal of free extracellular DNA from environmental samples using ethidium monoazide and propidium monoazide. This technique can help to reduce background noise and improve the detection of extracellular bacteria, as it selectively targets and removes free DNA that is not associated with viable cells.

Challenges in Quantifying Extracellular Bacteria

While the detection and quantification of extracellular bacteria have advanced significantly, there are still some challenges that researchers face. One of the main challenges is the potential for extracellular DNA to persist in the environment, even in the absence of viable cells. This can lead to an overestimation of the abundance of extracellular bacteria, and researchers must employ strategies to differentiate between free DNA and DNA associated with living cells.

Additionally, the complex interactions between extracellular bacteria and their environment can make it difficult to accurately measure their activity and impact. Factors such as nutrient availability, pH, temperature, and the presence of other microorganisms can all influence the behavior and physiology of extracellular bacteria, complicating the interpretation of experimental data.

Intracellular Bacteria: Challenges and Approaches

In contrast to extracellular bacteria, intracellular bacteria reside within host cells, making them more challenging to detect and quantify. These bacteria can evade the host’s immune system and establish chronic infections, posing a significant threat to human health.

Imaging Flow Cytometry (IFC)

One powerful tool for studying intracellular bacteria is imaging flow cytometry (IFC). This technique combines the high-throughput capabilities of flow cytometry with the visual information provided by microscopy, allowing researchers to quantify morphological cellular features and identify intracellular bacteria within host cells.

IFC has been particularly useful in the study of intracellular pathogens, such as Salmonella and Listeria, providing insights into their infection dynamics and host-pathogen interactions. By combining IFC with other techniques, such as fluorescent labeling and genetic analysis, researchers can gain a more comprehensive understanding of the behavior and impact of intracellular bacteria.

Genome-scale Reconstruction and Modeling

Another approach to studying intracellular bacteria is through genome-scale reconstruction and modeling. This involves the development of computational models that simulate the physiology and behavior of these bacteria, based on their genomic and metabolic information.

While this approach is still in its early stages, it has the potential to provide a predictive understanding of the dynamics of intracellular bacteria, including their interactions with host cells and the impact of various environmental factors on their growth and survival. By integrating this knowledge with experimental data, researchers can develop more effective strategies for combating intracellular bacterial infections.

The Importance of Understanding Extracellular and Intracellular Bacteria

The distinction between extracellular and intracellular bacteria is not always clear-cut, as some bacteria can switch between these states depending on environmental conditions. For example, the opportunistic pathogen Pseudomonas aeruginosa can cause chronic lung infections by producing quorum sensing (QS) molecules that enable biofilm formation and antibiotic resistance.

Understanding the dynamics of extracellular and intracellular bacteria is crucial for developing effective strategies to combat bacterial infections and promote human health. By leveraging the latest techniques in detection, quantification, and modeling, researchers can gain a deeper understanding of the role of these bacteria in various biological systems, from natural environments to the human body.

In conclusion, the study of extracellular and intracellular bacteria is a rapidly evolving field, with new technologies and approaches constantly emerging to improve our understanding of these microorganisms. By staying up-to-date with the latest research and applying these insights to real-world challenges, we can work towards a future where bacterial infections are more effectively managed and controlled.

References:

1. Nagler, M., Insam, H., Pietramellara, G., & Ascher-Jenull, J. (2018). Extracellular DNA in natural environments: features, relevance and applications. Applied Microbiology and Biotechnology, 102(23), 6343-6356.
2. Wagner, A. O., Malin, C., Knapp, B. A., & Illmer, P. (2008). Removal of free extracellular DNA from environmental samples by ethidium monoazide and propidium monoazide. Applied and Environmental Microbiology, 74(9), 2537-2539.
3. Extracellular Microbial Metabolomics: The State of the Art. (2017). PMC.
4. How to Count Our Microbes? The Effect of Different Quantitative Microbiome Profiling Approaches on Microbial Load Quantification. (2020). PMC.
5. Quantifying bacterial fitness in intracellular dynamics. (2019). bioRxiv.

The introduction of species may be deliberately or accidental from its natural habitat to alien or foreign one.

An exotic species means any plant or animal species that are non-native. It is also called invasive species, introduces species or alien species.

Exotic species examples

1. Strongylocentrotus purpuratus
2. Kudzu
3. Cortaderia jubata
4. Hedera helix
5. Reynoutria japonica
6. Centaurea solstitialis
7. New Zealand mud Snail
8. Feral pig
9. European rabbit
10. Gray squirrel
11. Cyprinus carpio
12. Ferret
13. Nepenthes
14. Hura crepitans
15. Mimosa pudica˙
16. Rafflesia arnoldii
17. Victoria amazonica
18. Eucalyptus
19. Vachellia drepanolobium
20. Titan arum
21. Greater one-horned Rhinoceros
22. Nilgiri tahr
23. Bengal tiger
24. Asiatic lion
25. Black buck
26. Lion tailed macque
27. Snow leopard
28. Malabar Giant Squirrel
29. Gee’s Golden Langur
30. Dugong
31. Giant flying Squirrel
32. Himalayan Tahr
33. Red Panda
34. Hangul
35. Flying fox
36. Nilgiri Marten
37. Himalayan Marmot
38. Himalayan Brown Bear
39. Indian Chevrotain
40. Honey Badger

Strongylocentrotus purpuratus

The S. purpuatus common name is purple urchin found along the Eastern Edge of the Pacific Ocean divergenting from Ensenada, Mexico to British Columbia, Canada. The urchin species live in nearshore sub-tidal and lower inter tidal communities.

Kudzu

The kudzu also called Chinese arrowroot or Japanese arrowroot. It is the group of coiling, climbing or perennial vines native to East Asia, Southeast Asia and some Pacific islands. It is invasive to the North America.

Cortaderia jubata

It is grass species known as Andean pampas grass or purple pampas grass. The C. jubata is the grass species native to the Northern Andes but on other part it is considered as alien species.

Hedera helix

It is known as the common ivy, European ivy , English ivy or simle ivy. It is the flowering species native to most of europe and Western Asia. It is evergreen ivy.

Reynoutria japonica

It is the herbaceous perennial plant native to East Asia in Japan, China and Korea. Its common names are Japanese knotweed or Asian knotweed. It is invasive in many part of world.

Centaurea solstitialis

It is called as yellow star-thistle native to the Mediterranean Basin region. It also known as yellow cockspur, Barnby thistle or Golden star thistle.

New Zealand mud Snail

The Potampyrgus antipodarum ( new Zealand mud snail) is the freshwater snail native to New Zealand but it is extend to many other countries. The snail is having a gill and an operculum.

Feral pig

It is domestic pig which gone feral (lives in wild). They found in the America and Australia. The species is known as Sus scorfa.

European rabbit

The species Oryctolagus cuniculus , the common name coney is the rabbit native to the Western France, Iberian Peninsula ( including Spain, Portugal and Southwestern France) and Northern Atlasmountains in Northwest Africa.

Gray squirrel

The gray or grey squirrel refer to several species to indigenous to North America.Eastern gray squirrel introduced un UK,Ireland, WesternNorth America , Italy, Western Africa; from Eastern US and southeastern Canada. The western gray squirrel from Western US.

Cyprinus carpio

This the species of carp , an oily freshwater fish native to the Europe and Asia. Carp as a food consumed in. many part of the world. It is considered as invasive in Africa, Australia and most of the US.

Ferret

The ferret is domesticated form of the wild European ferret . the species name is the Mustela furo. The black footed ferret is endangered species in the North America .

Nepenthes

It is the pitcher plant having distinct features as its leaves of pitcher shape. they are common in tropical forests of Borneo, the Philippines and Sumatra.

Sandbox tree

This is evergreen tree native to the tropical region of America. The bark of tree adapted in cone shaped spike as a adaptation for its protection. It is often called as monkey no climb due to its spikes. The species name is Hura crepotans.

Mimosa pudica

This is very few sensitive plant species which can move rapidly. It is found to its natural habitat in the South and Central America. Due to its ability to move, it is widespread all over the world.

Rafflesia arnoldii

It is also called Corpse Lily , the alien looking flower native to the Sumatra and Borneo. It is difficult to locate, it blooms once per year and for few days.

Victoria amazonica

The common name , water platter is of pan like shape. The bigger leaves bear the weight of a human. They are found in the Amazon.

Eucalyptus

They are native to the Australia but now a days they are found every part of world. The eucalyptus oil is used in many medicines and beauty commercially. The tree are highly flammable.

Vachellia drepanolobium

Commonly called whistling thorn tree is the acasia tree species native to the East Africa. The common came out from the whistling sound produced by the thorn like leaves that made ant-made entry holes when the wind blow.

Titan arum

These are enormous flower with a nauseating (foul) smell native to the Western Sumatra.

Greater one-horned rhinoceros

The rhinoceros are listed as vulnerable species by IUCN. It found in the India and Nepal specifically in the Himalayas foothills. Horn poaching is the main reason for its decline in number.

Nilgiri Tahr

It is a mountain ungulate native to the tropical rainforest of the Western Ghats of India.Due to poaching and eucalyptus cultivation, its habitat affected, thus continuously decreasing.

Bengal tigers

The Bengal tigers native to the tropical evergreen forests, deciduous forests, thorn forests, mangrove swamps and grass jungle sin India and Bangladesh. The tiger population decline rapidly due to poaching and human interference.

Asiatic lion

It is also called Indian Lion or Persian lion. Gujarat, India is the native place of Asiatic lion. It is second largest feline species in the world, first one are tigers.

Black buck

The Indian antelopes, found in the grassland, plain and scrubs in India, Nepal and Pakistan. Drastic downward fluctuation in the population due to overgrazing, habitat destruction, hunting and inbreeding.

Lion Tailed Macaque

The lion tailed macaque native to the Western Ghats of India. It is the old world monkey.

Snow Leopard

Snow leopard is the descendant of panther families. The home of the snow leopard in the Himalayas of India. Habitat loss and hunting is the main reason for the population decline of the snow leopard.

Malabar Giant Squirrel

The Malabar giant squirrel also known as Shekru, is a rodent species found to throughout the Western Ghats up to the Satpura Range of India.

Gee’s Golden Langur

It is highly endangered species native to the Indo-Bhutan border only in Assam. Distinct feature is they change their fur color as per seasons.

Dugong

These are sea cows, mammals found in warm coastal water of the Indian Ocean.

Giant Flying Squirrel

The most of species of the giant flying squirrel are native the northeastern states of India. While flying, their flying membrane extends from their ankle to wrists which help them to glide from one tree to other.

Himalayan Tahr

It is sub species of wild goat , native to the snow covered mountains of the Himalaya, India

Red Panda

These little mammals found in the forests of Sikkim, Darjeeling, Western Arunachal Pradesh and some parts of Meghalaya states of India. It is also Sikkim state animal.

Hangul

It is subspecies of deer native to Jammu and Kashmir, India. Common name is Kashmir Stag, considered as critically endangered.

Flying fox

Basically they are fruit bats but due to resemblance to fox called as flying foxes. They are native to South Central Asia.

Nilgiri Marten

They found in the Western Ghats, India. This is small carnivore mammals.

Himalayan Marmot

They found at the very high altitude of the Himalaya ,India. These are best adapted to oxygen-starved environments.

Himalayan Brown Bear

They are only native to India and Pakistan. Extinct in the Bhutan.

Indian Chevrotain

These are nocturnal ( found only in dark or night) species found in semi-evergreen and deciduous forests of Karnataka, Telangana and Chhattisgarh,State of India.

Honey Badger

The honey badgers are native to the forests of Africa and India. These ferocious animals have exceptional defensive abilities.

Please click to learn more about Herb Plant Example. Also, you can learn on Flagship Species Examples.

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Endemic species are the species which are found in a defined single geographical region, like a state, nation, country, island or other defined zones.

The endemic species either flora or fauna is native and restricted to a certain place, if find in any other geographical region than it will be not considered as endemic species

Endemic Species Examples

here we list out few endemic species as follows

1. Cape sugarbird
2. Cytisus
3. Clinotarsus curtipes
4. Orange breasted sunbird
5. Amphipsalta zelandica
6. Aplastodiscus arildae
7. Devil hole pupfish
8. Giant Panda
9. Norway Lemming
10. Scottish Wildcat
11. American Alligator
12. Pygmy Three-Toed Sloth
13. Poison Dart Frog
14. Glacier Bear
15. Chiribiquete Emerald
16. Sclater’s Monkey
17. Patagonian Mara
18. Southern Adder
19. Sri Lankan Birdwing
20. Brookesia Micra
21. Wilson’s Bird of Paradise
22. Platypus
23. Kiwi
24. Matschie’s tree kangaroo
25. Ilex gardneriana
26. Vateria indica
27. Hydrophila madurensis
28. Hopea parviflora
29. Pterocarpus santalinus
30. Nepenthes khasiana

Cape sugarbird

Cape sugarbird (Promerops cafer) is the bird or aves species which are endemic to the Fynbos biome of the western cape and Eastern cape of South Africa. It is a grey-brown colored bird that is spotted by presence of yellow spot under the tail and in males, a very long feathers present. Another feature of the Cape sugarbird is its sound while flying. When the male bird beats its wings, due to its main flight feathers arrangement made a sound of frrt-frrt with the intention to attract the female birds

Cytisus

It is the flowering plant inhabits to the open site in Europe, North Africa and Western Asia. It is also known as brooms in several tribes. these are kind of shrubs producing highly fragrant, brightly colored, pea like flower.

Clinotarsus curtipes

Clinotarsus curtipes also called as “Malabar frog” or “ bicolored frog”. It is endemic to the Western Ghats of India. The species’ tadpoles are black in color , form compact and dense schools in the streams in the forested areas. The frog vomerine teeth are not fully developed, they are two slightly oblique series with the choanae hind edge. It is greyish or brown in color above, with or without blackish dots; edged black; lateral fold lighter; band or a blackish oblique spot below eye; blackish margins with upper lips; throat sometimes dark brown; limbs without bands, dark purplish brown. Male frog having internal subgular vocal sac.

Orange breasted sunbird

The orange breasted sunbird (Anthobaphes violacea) is a small, nector feeding bird that is endemic to the fynbos shrubland biome of Southwestern South Africa. The sunbird is dimorphic sexually as female is olive green in color and males are orange to yellow. Male bird is longer than female.

Amphipsalta zelandica

The Amphipsalta zelandica (chorus cicada) is the cicada species endemic to the most areas of New Zealand. They live in forests. They found in area with open bushes where on the trunk and branches, their leftover nymph skins can be seen specially in summer season.

Aplastodiscus arildae

It is the frog spesies belongs to the family Hylidae. It is endemic to Brazil and frogs’ natural habitats are troplical or subtroplical moist lowland rivers and forests.

Devil Hole Pupfish

The devil hole pupfish (cyprinodont diabolis) is found only in Devils Hole, a water filled cave in the US state of Nevada. It is small fish with length upto 30mm. male fish are bright metallic blue and female are yellowish in color. Lack of pelvic fins are specific traits of this fish.

Giant Panda

The giant panda are endemic to the China. They are considered as a national treasure there. Around 1900 giant pandas are alive today on in the wild.

Norway Lemming

Norway lemming are endemic to the Norway. They are also known as Norwegian lemmings.

Scottish Wildcat

Scottish wildcat are endemic to the Scotland. While in Scotland, Scottish cats and dogs drool are very common. At the first look, they look very similar to the house cat but the wildcat have larger brains and different shape of pupil of eyes.

American Alligator

The American alligator are endemic to the Florida of USA.at present they may be thriving but later in past the alligator was endangered and at the point of extinction

Pygmy Three-Toed Sloth

The Pygmy Sloth are the smallest among all kind of Sloths. They are endemic to the Isla Escudo de Veraguas, kind of a small island off the Panama coast. The body length of Pygmy Sloth is between 19 to 21 inches and their weight is 5.5-7..7 pounds only

Poison Dart Frog

These species of frog are endemic to the Costa Rica and South America. They are very colorful but yet very poisonous. The toxicity of poison of Dart Frog vary by the species but some are so poisonous can kill a person. They are very tiny( some are less than one inches),very difficult to spot.

Glacier Bear

The Glacier Bear also called the blue bear. They are endemic to the Alaska, USA. It is the American black bear having silver-blue or gray fur.

Chiribiquete Emerald

This is type of humming bird which is endemic to the Southern Colombia. It is almost fluorescent blue and green color humming bird.

Sclater’s Monkey

This species of monkey is only 11 in number and endemic to the Nigeria. Their most distinct feature is the presence of white tufts of hairs on each ear.

Patagonian Mara

It is endemic to the Argentina. They are herbivore large rodent look like cross between a rabbit and a kangaroo. They are fourth-largest rodent in the world.

Southern Adder

It is the venomous snake endemic to the low-lying coastal areas of the Western Cape. The snake have small horn above each eye.

Sri Lankan Birdwing

It is the species of butterfly endemic to the Sri Lanka only, considered as a national butterfly of the country. Its big wings having bright yellow pops and is the largest butterfly on the island

Brookesia Micra

It is the species of chameleon which is smallest of size only 29mm long. They do change the colors. It is endemic to the Madagascar.

Wilson’s Bird of Paradise

It is the most colorful bird in the world endemic to the Indonasia. The distinct feature is bright blue head and curled tail feathers.

Platypus

The semi-aquatic mammal endemic to the Eastern Australia. This is best known for its duck-like bill. The male platypus are venomous.

kiwi

It is the type of bird which cannot fly with strong kegs but no tail. They are endemic to the New Zealand.

Matschie’s tree kangaroo

It is endemic to the Papua New Guinea. The local people called it as “ ghost of forest”.

Ilex gardneriana

It is critically endangered to the Nilgiri Hills of India

Vateria indica

The Vateria indica ( white dammar) is the plant species endemic to the Western Ghats in India. Habitat loss is the main reason of threatened of species.

Hydrophila madurensis

It is the species of aquatic plant critically endangered. It is endemic to the Nallakulam in the Alagar Hills of the Eastern Ghats in Tamil Nadu, India

Hopea parviflora

It is the plant species endemic to the India. This tree is timber producing and commonly harvested from the forests.

Pterocarpus santalinus

Tha common name of tree are red sanders, Chenchandanam, red sandalwood, Rakta Chandana, red saunders, Yerra chandanam and saunderswood. The plant species is endemic to the Southern Eastern Ghats range of South India. The tree valued due to its rich red color of wood.

Nepenthes khasiana

It is endemic to the Khasi Hills , India. It is the only pitcher plant species in India. It aatract the prey by the means of blue color fluorescence.

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Singular coccus; plural cocci is the type of bacteria which is of spherical, oval or round in shape.

Coccus mainly refers to the bacteria shape and can grow in chains, clusters or pairs depends on their attachments during cell division.

let us discuss some examples of cocci bacteria

• Neisseria
• Moraxalla catarrhalis
• Diplococcus pnemoniae
• Enterococcus spp.
• Streptococcus spp.
• Stapylococcus spp.
• Micrococcus spp.
• Sarcina spp.

Bacterial classification

Bacteria are classified mainly into three types depending on their shapes.

• Cocci – they are spherical in shape
• Bacillus– they are rod or cylindrical in shapes
• Spirochetes– they are spiral in shape

Characteristics of coccus bacteria

The name ‘coccus’ is derived from the Greek word ‘kokkus’ which means Berry. Their size ranges vary from 0.5 to 1.0 µm in diameter. These are smallest and simplest form of bacteria.

Structure of cocci

The cell wall structure of cocci may vary from gram –ve bacteria having thin peptidoglycan layer and Gram +ve bacteria which have thick peptidoglycan layer in their cell wall. Cocci bacteria may be of pathogenic, symbiotic or commensally in nature.

Comparison with other bacteria

Coccus bacteria v/s bacillus bacteria

Coccus bacteria are spherical or oval in shape while bacillus bacteria is of rod or cylindrical in shape e.g., Escherichia coli, Bacillus subtilis.

Gram +ve bacteria v/s Gram –ve bacteria

Bacteria can be differentiated into two categories based on the property of dye attained by bacterial call wall used in gram staining method. Gram –ve bacteria have a thin peptidoglycan cell wall whereas gram +ve bacteria have large, thick membrane.

Types of cocci bacteria

Cocci bacteria can exist in mainly four categories depand on their grouping and arrangement of cocci cell.

• Diplococcus bacteria- As the name indicate ‘diplo’ means in pairs that is when two coccus cells are connected in pairs. They can be of any type gram +ve or gram –ve bacteria. Example – Neisseria gonorrhoea causes disease gonorrhoea, Neisseria meningitidis causes a type of meningitis, Diplococcus pneumoniae causes pneumonia disease.
• Streptococcus bacteria- these are the bacteria arranged in chains or row. The length of chain may vary. These are gram +ve bacteria. Example – Streptococcus pneumonia causes pneumonia, meningitis and bronchitis; Streptococcus pyogene cause tonsilitis and strep throat.
• Staphylococcus bacteria- These are the bacteria are arranged in grape like cluster of coccus cells. These are gram +ve and halo tolerant (can survive at very high concentration of salt). They are also non-motile in nature. Example- Stapylococcus aureus causes pneumonia and skin infection; Staphylococcus epidermis causes common part of normal skin flora; Stapylococcus haemolyticus found in hospital skin infections.
• Enterococcus bacteria- These are the bacteria arranged in pairs or short chains. These are gram +ve, non- motile, and live in enteric nervous system. Enteric bacteria has limited capacity to cause diseases. Example- Enterococcus faecalis and Enterococcus facieum causes infection in intestine.

Arrangement of cocci cells

During the cell division, cocci cells may remain single or attached. Cells which are attached can be divided depend on their arrangement.

• Diplococci – cocci cell are remain in pairs (group of two cells). e.g. Streptococcus pneumoniae and Neisseria gonorrhoeae.
• Streptococci – cocci are present as chains e.g. Streptococcus pyogene.
• Staphylococci – cluster of cocci are irregular like grapes shape e.g. Staphyococcus aureus.
• Tetrad- cluster of four cocci arranged in the same plane e.g Micrococcus sp.
• Sarcina– eight cocci are found to be cuboidal arrangement e.g. Sarcina ventriculi.

Common example of cocci bacteria

Gram negative diplococci – Neisseria spp. And Moraxella catarrhalis.

Neisseria

these are the bacteria that make colony on mucosal surfaces of many animals. Out of 11 species that colonize human but only two are pathogens which are N. meningitis and N. gonorrhoeae. When they are examined under microscopically appeared as coffee beans. N. gonorrhoeae also called gonococcus responsible to causes gonorrhea disease and N. meningitidis also called meningococcus is the common cause of bacterial meningitis and responsible for meningococcal septicaemia

Moraxella catarrhalis

it is a non motile, oxidase positive and aerobic diplococcus that is responsible for infections of central nervous system (CNS), respiratory system, middle ear, eye and human joints.

. Gram negative diplococci– Streptococcus pneumoniae and Enterococcus spp

Diplococcus pneumoniae

they are non motile and do not form any find of spores. D. pnemoniae is the significant human pathogenic bacteria were recognised to be cause pneumonia in late 19th century. It lives asymptomatic in healthy carrier mainly in respiratory tract, nasal cavity and sinuses. While in persons with weak immune system like young children and elderly people, it may become pathogenic and cause diseases by spreading to other locations. It can be causative agent of neonatal infections. It spreads by person to person contact directly through respiratory droplets.

Pneumonia diseases caused by the bacteria D.pnemoniae, different type of vaccines have been developed to protect from its infections. The WHO (World Health Organisation) recommends routine pneumococcal vaccinations in childhood.

Enterococcus spp.

In the past Enterococcus bacteria thought to be harmless to humans but within last decade, there has been influx of nosocomial pathogens that were originating from Enterococcus bacteria. The bacteria cause enterococcal meningitis, a nosocomial disease. These nosocomial infections (originates from a hospital) also affects the urinary tract (UT) and post- surgical wounds that still in healing condition.

Streptococcus spp.

in streptococci, cell division occurs along a single axis, so at successive division they may appear bent or twisted. Most of them are catalase negative, oxidase negative and facultative anaerobes (able to grow in both aerobic and anaerobic conditions).

In addition to streptococcal pharyngitis (strep throat) certain type of Streptococcus species causes many diseases like pink eye, meningitis, bacterial pneumonia, endocarditic, necrotizing fasciitis (flesh eating bacterial infection) and erysipelas.

Many species of streptococcal are not pathogenic whereas commensally human microbiota of skin, mouth, upper respiratory tract and intestine. Streptococci bacteria are also helpful in producing Emmentaler (swiss) cheese.

Streptococcus species further classified based on their hemolytic properties.

1. Alpha-haemolytic species – these are species which cause iron oxidation in haemoglobin molecules within red blood cells.
2. Beta-haemolytic species- species that cause complete red blood cells (RBCs) rupture.
3. Gamma-haemolytic species – these species do not causes any type of haemolysis

Stapylocococcus spp.

they appear spherical (cocci) and form in the grape like cluster. Staphylococcus species are facultative anaerobic (able to grow in both aerobic and anaerobic conditions).

Many species cannot cause diseases and inhabit normally on skin and mucous membrane of human and other animals. Certain species found to be nectar inhabiting microbes and also a small component of soil microbiome.

Two species of Stapylococcus (S.epidermidis and S. arlettae) identified as halotolerant (salt tolerant).

Micrococcus spp.

these are species found in a wide range of environments like soil, water and dust. These are gram- positive spherical cells vary from 0.5 to 3 µm in diameter and typically arranged in tetrad. They are oxidase positive, catalase positive, citrate negative and indole negative.

Earlier Micrococcus is thought to be a commensal or saprotrophic bacteria but it can be an oppotunistic pathogen, which particularly found in the hosts with compromised (weak) immune systems, such as HIV patients. Micrococci may be involved in many type of other infections like recurrent bacteremia, septic arthritis, septic shock, meningitis, endocarditis and cavitating pneumonia (immunosuppressed patients).

Sarcina spp

its name from the Latin word “sarcina” means pack or bundle. They divide in the three planes and arranged in cubodial (2×2×2) arrangement of cocci cells. Most of the members of this genus are human flora and microbial cellulose synthesizer.

The species Sarcina ventriculi found in the cereal seeds surfaces, mud, soil and in the stomachs of humans, rabbits and guniea pigs.

Frequently asked questions-

Q1 what is the shape of cocci bacteria.

• 1. Rod shaped
• 2. Cylindrical
• 3. Spiral
• 4. Spherical

Ans. The correct answer is option 4

Q2 What are arrangement of cells in Staphylococcus bacteria

• 1. Tetrad
• 2. Cuboidal
• 3. Grape like
• 4. Irregular

Ans the correct answer is option 3

Q3 what kind of cell arrangement found in the Streptococcus bacteria

• 1.Row
• 2. Chain
• 3.Tetrad
• 4.Both a and b

Ans the correct option is option 4

Q4 What is Nature of cocci bacteria

• 1. Gram positive
• 2. Gram negative
• 3. Both a and b
• 4. None of the above

Ans the correct option is option 3

Q5 The disease gonorrhoea is caused by which bacteria

• 1. Neisseria gonorrhoea
• 2. Staphylococcus aureus
• 3. Streptococcus pnemoniae
• 4. Bacillis subtilis

Ans the correct answer is option 1.

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